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  #1  
Old 02-16-2000, 03:07 AM
richardd richardd is offline
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I have a 71 Challenger conv. with a 383, which is at least date correct if not numbers matching (I will know for sure after steam cleaning), that I want to mothball. In its place I want to build a outwardly stock appearing street motor that will run on pump gas and perform real well. This is an A/C car with an automatic.

There seems to be a good supply of 400 blocks in my local salvage yard. I am leaning towards a stroker motor that can be built with reconditioned salvage parts. I have read the threads on 451 motors and wanted to see if something like that would make sense for the street.

I am looking for crank-rod-piston combinations and the specifications/instructions that I would need to give to my machine shop. I have the Mopar Muscle 11/99 issue detailing the 440 crank installation.

Starting with the 400 block. Are there any years that should be avoided? Do I start with any stock 440 crank or is there a desirable casting number that works better or will save machining labor? Same for the rods.

What pistons should I use and how much should I mill the heads for pump gas (assume .020 over).
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Old 02-16-2000, 05:46 AM
JR JR is offline
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richardd,
According to some books of mine, the 400 was basically a bored out 383. I know this isn't what you asked but bare with me for a minuite. The 400's purpose was to replace the base 383 in non-performance applications,
while the 383 Mag was built to haul a$$. The 383 has the forged crank and the other good stuff. I'm not sure about the 400.
I don't think the 400 would be any better than the 383.
Reason 1. Hi-performace parts seem to be easier to find for the 383.
Reason 2. A big block Challenger is all motor anyway
Reason 3. You could overbore the 383, and still retain the forged parts, and have a correct dated engine
Reason 4. The 400 needs higher compression and a better set of heads to run fast.
Reason 5. The 400 wasn't intended to be a performace engine. Unlike the 383.
I don't know if any of this makes sense, but I tried to help. My final words.........
Build up the 383.
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  #3  
Old 02-16-2000, 06:38 AM
Maxwedge Maxwedge is offline
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In the short term, maybe over boring the 383 would be good, but what about 50 years later. Because you pushed the motor so hard now it is highly unlikly that the motor would have survived 20-30-50 years later. A 400 is cheap and the 383 is irreplacable.
I would say dont screw with the 383. Pull it and the original tranny and if your going to race it pull the rear. The whole drive train is relativly cheap to replace. A few hundred bucks. But if you trash an original part how much less is your car worth????
ALOT less.
but thats just my opinion and its not my car
Max
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  #4  
Old 02-16-2000, 10:23 AM
PRO PRO is offline
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Richard it sounds like a cool car anyway how fast do you want to go in the 1/4?if your looking for 12.00 or so I'd stick with a typical 440 and save the extra "stroker" dollars to spend on something else. If your set on a faster 1/4 time then call Muscle Motors and ask for a brochure this will give what your looking for.Youll spend around $1800 more $ to build a stroker than a typical 440.Hope this helps ....PRO...
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Old 02-16-2000, 10:49 PM
richardd richardd is offline
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My goal is to have a car that will run mid 13s or perhaps better and handle the A/C. My reason for going with a 400 is the apparent availabliity of core engines in the salvage yards. In the salvage yards in my area the 383s have be grabbed up for the 906 heads and the only 440s left are truck/RV versions.

Cost is a definite concern. Would I be better off starting a 440 from an RV instead of a 400?
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Old 02-16-2000, 11:57 PM
Maxwedge Maxwedge is offline
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The disadvantage of the conversion 440's is the cast crank and rods, but if all your going to do is do 13's...They should be able to handle it. The cool thing is they "Should" have the 452 heads, the unleaded heads...COOL. If you do go that way,(the 440) get a new cam and valve springs. Other than that make sure the carb is good and everything else is solid and 13's shouldnt be a problem.
Screwing around with the 383 is a bad idea if you plan on actually driving it more than a few times a year...That car is rolling gold with all the original stuff after all..
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  #7  
Old 02-17-2000, 07:02 PM
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AZMOPAR AZMOPAR is offline
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There is no physical outward difference between a 383 and 400 block except casting numbers - Muscle Motors has a steel crank kit for the 400 that provides all parts and is very reasonable.. info from their web page..
this is probably easiest way for a stealth conversion... Id say go for it.

451 Kits: This is the 440 crank in the low deck block trick. This is an excellent kit providing great performance in a small package. 400 block provides 451 CID, 383 block makes a 431. Great for a sneaky restoration rebuild! No special block work or grinding required! Components:440 steel crank ground and polished, specially machined counterweights for block clearance and weight reduction. Ross or KB pistons, Fully prepped rods w/ARP bolts, C&A or Sealed Power rings, M77 rod & full groove main bearings. Balanced, ready to install.
KB Kit: $1599 Ross kit: $1799
Options: Domed pistons add $60, file fit rings add $70, Eagle steel rods add $495, BME
aluminum rods add $595
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  #8  
Old 02-18-2000, 06:07 AM
Belvedere Belvedere is offline
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For the street there is no substitution for cubic inches. If you have the correct 383 for your car it's a lot more valuable with no windows in it. The 451 will be more bucks to put together, but if you want the appearance of your 383, build the 451 and tell everyone it's just well tuned 383. The 451 will be all new parts and make more horses because you were going to spend money any way. The 440 in stock or near stock form is the best low dollar way to get to low 13s. They did that from the factory with just a little help The 440 can be built much bigger and cost a whole lot of money too. You have look at your budget and how much value you want to put what "looks" like a 383. If you go 451 try to find a 71-72 pickup block. I wouldn't go past 76 for a nasty motor.
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  #9  
Old 02-19-2000, 04:20 AM
richardd richardd is offline
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Do the Muscle Motors 451 kit use a forged crank? Since all 400 cranks are cast would I then have to use a damper from a forged crank motor?

Do these kits require custom pistons? Will I be able to get a 9.5:1 compression without milling the heads? If not, what combination (pistons, milling, gasket) will get me the closest to that CR.
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  #10  
Old 02-20-2000, 05:50 AM
Belvedere Belvedere is offline
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Muscle motors will use a forged or cast crank. It's up to you. The dampener will be for 440. You might look at an after market balancer. I used a Fluidampener. I have Ross pistons #99499 and I think the compression was 12.5 to 1 before we modified the heads and decked the block. My compression is close to 13.7 to 1 now. I'm sure a lower ratio would be available and you could have the pistons "shaved" to lower it some more if 9.5 is your goal for the poor fuel found on the street. Talk to the guys at Muscle Motors I think Eric is their tech guy. They have kits for just about any need.
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  #11  
Old 02-20-2000, 06:55 AM
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The Dartman The Dartman is offline
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Go for that RV 440 first - I hear they have extra "steam holes" that make them run cooler.

I have a buddy who has an 2900 pound 74 Duster ex pro stocker running 10.30's with a motor home block with stage VI heads.

------------------
'73 Dart Sport
318 CU, 12.5:1, "J" Heads, 517L/292D Camshaft
727 trans, 4500 Tci Converter back to 4.30 gears for a best of 12.87@105
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